let str = ' abcdefg '
console.log(str.reverse());

// let str2 = str.concat('def')
// let str2 = str.substring(1, 4)


// let s = '0123542134@qq.com'
// console.log(s.endsWith('@qq.com'));



// console.log(s.padStart(10, '0'));
// let a = '1232135324131654321'
// let b = '0000000000000987654'


// let a = '123'
// console.log(parseInt(a, 2));

let arr = [1, 2, 3]

let res = arr.map(parseInt)  
// parseInt(1, 0)
// parseInt(2, 1)
parseInt(3, 2)

// console.log(res); // [1, NaN, NaN]

